A Digital Micro-mirror Device (DMD) allows an image to be projected onto a road surface, which is also known as road writing. Road writing requires a combination of an image projection pattern and a complementary pattern. The complementary low beam lamp pattern needs to be adapted to create a dark region in the foreground to allow the addition of the image projection pattern. The dark region needs to provide a sufficient contrast for the projected image to create a clear image on the road surface.
One road-writing system includes a low beam lamp pattern with a flat beam and a specialized kink beam near cutoff, plus a road-writing projection. The flat portion of the beam needs to be asymmetrical to create a proper tunnel in the near foreground for the projected image.
FIG. 1A illustrates a low beam luminous distribution for a left headlamp with a DMD road-marking distribution portion 10, a kink flat distribution portion 20, a flat beam distribution portion 30, a DMD Adaptive Driving Beam (ADB) distribution portion 40, and a complementary high beam distribution portion 50. FIG. 1B is a symmetrical low beam luminous distribution for a right headlamp with the DMD road-marking distribution portion 10, the kink flat distribution portion 20, the flat beam distribution portion 30, the DMD Adaptive Driving Beam (ADB) distribution portion 40, and the complementary high beam distribution portion 50. As illustrated in FIGS. 1A and 1B, the beam distribution patterns spread about 30° right for the left headlamp distribution and about 30° left for the right headlamp distribution.
When a DMD image is projected, light from the right headlamp covers the left headlamp in order to make an opening in front of the vehicle for the DMD projection. However, with a conventional headlamp, there is no opening where the luminous distribution spreads right and left beyond the vertical axis. Therefore, in order to create an opening in front of the vehicle for a DMD image projection, the left headlamp distribution needs to spread to the left with no spread to the right, and the right headlamp distribution needs to spread to the right with no spread to the left.
Unfortunately, certain vehicle headlamp requirements fail this particular luminous distribution pattern because there is no light at approximately the 15° or 20° distribution point. In addition, this distribution pattern can have poor homogeneity for a low beam luminous distribution. Also, the DMD road marking portion 10 is activated at all times to fill the newly-created opening in the luminous distribution pattern.
The “background” description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description which may not otherwise qualify as conventional art at the time of filing, are neither expressly nor impliedly admitted as conventional art against the present disclosure.